An investigation has been launched into yesterday's fire at Winter Hill.
Around 40 firefighters were called to tackle the blaze, near the Blue Lagoon, in Belmont at around 2.25pm on Friday (March 27).
Flames reached heights of six metres and approximately 2km of moorland was destroyed, according to fire officials.
It was initially believed to have been started by a BBQ but it is now being treated as deliberate and an investigation has been launched.
A spokesman for the Greater Manchester Fire Scene Investigation team tweeted: "Fire Investigation team assisted Lancashire Fire and Rescue Service investigate the wildfire near Blue lagoon Belmont yesterday.
"Based on info gathered we concluded the fire was started deliberately, by the car park.
"If you witnessed anything please contact Lancashire Police or Crimestoppers quoting 805."
Around eight fire engines remained at the scene until the fire was eventually extinguished just before 8pm.
Police said they were prepared to fine anyone not following current regulations at the scene.
Winter Hill was also the scene of devastating fires in the summer of 2018.
Lancashire Police has been contacted for comment.
